Since the end of 1980s, various microminiature sensors have been achieved with the development of the Micro-Electro-Mechanical-System (MEMS) technique.
Presently, the most widely used sensors mainly include MEMS pressure sensors and MEMS inertial sensors. The MEMS pressure sensor is a device for sensing pressure. Currently, the MEMS pressure sensor includes a Si-piezoresistive pressure sensor and a Si-capacitive pressure sensor, each of which is a micro-electro-mechanical sensor formed on a silicon wafer. The MEMS pressure sensors are widely used in various fields, for example, automotive electronics such as Tire Pressure Monitoring System (TPMS), consumer electronics such as tire pressure gauge and blood pressure gauge, industrial electronics such as digital pressure gauge, digital flow meter and industrial batch weighting.
The MEMS inertial sensor is a device which performs measurement by using inertia. In practical application, the MEMS inertial sensor generally refers to an accelerometer or a gyroscopic apparatus (which is also referred to as a gyroscope). According to different sensing principles, the MEMS inertial sensor may be classified into a piezoresistance sensor, a capacitive sensor, a piezoelectric sensor, a tunneling current sensor, a resonant sensor, a thermoelectric coupling sensor, an electromagnetic sensor, and the like. The MEMS inertial sensors are generally applied to the portable devices such as the mobile phones or the game devices in the consumer electronic field; are generally applied to the automotive electronic stability system (ESP or ESC) such as the car airbag or the vehicle gesture measurement or applied to the GPS assistant navigation system in the car field; and are generally applied to the communication satellite radio, the missile seeker or the like in the military or astronavigation field.
As described above, various sensors have been widely used in consumer electronics, automotive electronics and industrial electronics. However, due to the significant differences in manufacture and package method among various sensors, there is no integrated sensor product on the market now. Presently, the MEMS inertial sensor and the MEMS pressure sensor have been applied to the Tire Pressure Monitoring System (TPMS) of the car tire, but the existing acceleration sensor chip and the pressure sensor chip are designed and manufactured separately and then packaged together. For example, in the existing TPMS products manufactured by many companies (such as Infineon, Freescale, Bosch and GE), discrete inertial sensor chip, pressure sensor chip and signal processing circuit chips thereof are adopted and then packaged together, which causes a complicated overall process, a large size and a high cost. Such a method is described in U.S. Pat. No. 7,518,493 B2.